The beneficial effects of the support constraint on the improved thermal stability of supported titania membranes were studied by following the anatase to rutile phase transformation in supported and unsupported titania membranes. This was studied using Raman spectroscopy and XRD. Supported membranes showed a higher transformation temperature, about 150°C higher, (slower rate of transformation) compared to the unsupported ones. Unsupported membranes showed a slight thickness dependence on the phase transformation temperature, but less significant compared to the difference in phase transformation behaviour between supported and unsupported membranes of similar thicknesses.